Objective 4 - Weebly



Objective 4.01

Explain terms and procedures involving measurement tools.

• Explain measurement terms

• Explain measurement tools

• List measurement prefixes (see appendix)

• Explain the customary and metric systems of measurement (see appendix)

• Explain measurement conversions and calculations (see appendix)

“Technological knowledge and processes are communicated using symbols, measurement, conventions, icons, graphic images, and languages that incorporate a variety of visual, auditory and tactile stimuli.”(R1)

Measurement is the process of determining the size, amount or extent of something. It objectively describes the physical qualities of an object. It is also the practice of comparing qualities of an object to a standard.

There are two measurement systems used in the world today, the U.S. Customary System and the Metric System (System International, SI). The United States is the only industrialized country that has not adopted the metric system for everyday use.

The U.S. Customary system uses unique units for each quality being measured. The lack of uniform multiples can make the system confusing. It is based on units of measurement established during the Middle Ages in Europe. The basic units of measure for length is the inch; for weight, the pound; for volume, the quart; and for temperature, degrees Fahrenheit.

The Metric system was established in France. The basic unit of measure for length is the meter; for weight, gram; for volume, the liter; and for temperature, degrees Celsius.

Metric Prefixes – The metric system is based on ten. “ There is a logical progression from smaller units to larger ones, since all sizes of units are based on ten.”(p. 119, R3) The metric system starts with a base unit. Smaller units are decimal fractions of the base unit. Larger units are multiples of ten. The metric system uses a prefix to show us how the base unit has been changed. For example, the unit for distance is the meter. For large distances, the kilometer is used. The prefix kilo means 1000, so seven kilometers is equal to 7000 meters. For small distances, the millimeter is used. The prefix milli means 1/1000th. Twelve millimeters are 12/1000 of a meter. The metric system lends itself to easy use in mathematical formulas. The metric system uses the same prefixes for all base units.

Measurement Tools

Before a technician can measure anything using the customary or metric systems, they must first be able to explain how to use the appropriate measuring tools. Some measuring tools commonly used by technicians in their work include: rules, calipers, micrometers, squares, protractors, various gauges, weight scales, and calibrated containers.

Rules are used to measure length, width and thickness. Some rules used include: standard 12 inch rule, mechanical rule, drafter’s rule, machinist’s rule, metric rule, yard stick, meter stick, and tape measure. Rules are calibrated in many different ways. Technicians must be able to interpret calibrations when using rules.

Calipers are used to measure diameters on either the inside or outside of an object. The two types of calipers are the outside caliper and the inside caliper. Calipers may need to be used in conjunction with a rule to determine the value of a measurement. Many calipers are adjusted by turning it’s thumb screw until the legs fit snugly against the surface being measured. The distance between the legs is then measured with a rule.

Micrometers are very precise tools for measuring the length, thickness or diameter of small objects. A micrometer that uses customary units can measure to one thousandths (0.001) of an inch. A metric micrometer can measure to one hundredth (0.01) of a millimeter.

Squares are used to measure or lay out perpendicular lines (lines at 90 degree angles). Four commonly used squares are the try square, framing square, combination square, and center square. A combination square can also measure 45 degree angles.

Protractors are used to measure angles from 0 to 180 degrees for protractors that are half-moon shaped and 0 to 360 degrees for circular shaped protractors. Many protractors can also be used to measure length along their straight edge.

Weight scales measure weight or mass. Scales can range from the common bathroom scale to the most sensitive scientific scale. Scales can be analog or digital, manual or electronic. As you see, there are many factors to consider when selecting a scale.

Calibrated containers are used to measure volume. Cooks use calibrated containers to measure ingredients for recipes. Scientists use calibrated containers in the science lab. Measuring spoons, measuring cups, and lab beakers are three types of calibrated containers (R3, 117-129).

U.S. Customary System

The Basic unit of measure for length:

12 inches =1 foot

3 feet = 1 yard

1,760 yards = 1 mile

5,280 feet = 1 mile

The Basic unit of measure for weight:

16 ounces = 1 pound

2,000 pounds = 1 ton

The Basic unit of measure for volume:

8 ounces = 1 cup

2 cups = 1 pint (16ounces)

2 pints = 1 quart (32 ounces)

4 quarts = 1 gallon (128 ounces)

Notice the ounce is the unit of measure for both weight and volume. It is important to distinguish between weight and volume when using the ounce unit.

The basic unit of measure for temperature is in degrees Fahrenheit. The freezing point of water is 32*F. The boiling point of water at sea level is 212*F

Metric Measurement Prefixes

Base Units Base Units

giga = x 1,000,000,000 deci = x 1/10

mega = x 1,000,000 centi = x 1/100

kilo = x 1000 milli = x 1/1000

hecto = x 100 micro = x 1/1,000,000

deka = x 10 nana = x 1/1,000,000,000

pico = x 1/1000,000,000,000

Metric System

Using metric prefixes makes using the metric system very easy.

Length: The unit for length in the metric system is the meter. In the SI or metric system:

1000 millimeters = 1 meter

100 centimeters = 1 meter

1 kilometer = 1000 meters

Weight: The unit of weight in the metric system is measured in grams.

1 kilogram = 1000 grams

1 metric ton = 1000 kilograms

Volume: The liter is the basic unit of measure for volume in the metric system. Cubic centimeters are also used to measure volume.

1000 cubic centimeters = 1 liter

1000 milliliter = 1 liter

Temperature: In the metric system, temperature is measured in degrees Celsius. The freezing point of water on the Celsius scale is 0°C. There are 100 degrees between freezing and boiling on the Celsius scale, while on the Fahrenheit scale the difference is 180 degrees.

Converting Customary and Metric Systems

Because there are two systems of measure in use in the world today, it is sometimes necessary to convert measurements between the two systems. Technicians who use both systems in their jobs must do this frequently. By multiplying a measurement by the appropriate conversion factor, it is easy to change from one system to the other.

Use the following conversion factors to easily convert from customary to metric (SI):

Customary to Metric Conversion

Customary Units X Conversion Factor = Metric Units

Length Inches X 2.54 = centimeters

Feet X 0.3 = meters

Miles X 1.61 = kilometers

Weight ounces X 28.3 = grams

pounds X 0.45 = kilograms

Volume pints X 0.40 = liters

quarts X 0.95 = liters

gallons X 3.8 = liters

Metric to Customary Conversion

Metric Units X Conversion Factor = Customary Units

Length centimeters X 0.4 = inches

meters X 3.3 = feet

kilometers X 0.6 = miles

Weight grams X 0.035 = ounces

Kilograms X 2.2 = pounds

Volume liters X 2.1 = pints

liters X 0.26 = gallons

Temperature Conversions -Fahrenheit to Celsius (C = 5/9 ((F - 2)

Celsius to Fahrenheit (F = 9/5 (C + 32

Other Measurement Properties for Customary and Metric System

In addition to length, weight, volume and time, other properties exist for the Customary and Metric measurement systems. The following properties and their corresponding units of measure for the Customary and Metric systems are listed below:

Property Customary Unit Metric Unit

Area square inch square centimeter

square foot square meter

square yard square kilometer

square mile

Pressure Pounds per square inch kilograms per square millimeter

Energy foot-pounds Joules

British Thermal Units (BTU) calories

Power horsepower Watts

Speed miles per hour (MPH) kilometers per hour (KPH)

Force pounds Newtons

Torque foot-pound Newton-meters

The measurement of part and product size is important in technological design and production activities. Generally this type of measurement can be divided into two levels of accuracy, Standard Measurement and Precision measurement. (R3)

Standard Measurement

Many production settings do not require close measurements. The length of a house, the width of a playing field need not be very accurate. If the product is within a fraction of an inch it will work fine. These measurements are often given to the foot, inch or fraction of an inch in the customary system, or the nearest whole millimeter in the metric system.

The material being measured is also important. For example, wood changes (expands or shrinks) in size with changes in moisture content and the atmospheric humidity. Measurements closer than 1/32 in. or 1mm are not useful. Wood can change more than that in one day.

Standard measurements are common in cabinet and furniture manufacturing plants, construction industries, and printing companies. The printing industry uses its own system based on the pica (1/6in.) and the point (1/72in.)

Precision Measurement

Standard measurement is not accurate enough for many production applications. Watch parts and engine pistons would be useless if they varied by as much a 1/32in. (0.8mm).

These parts must be manufactured to an accurate size. For this type of production, precision measurement is required. Measurements of 1/1000 in. to 1/10,000 in. are precise in the customary system. Metric precision measurement will measure to within 0.01mm (one one-hundredth of a millimeter).

Direct Reading Measurement Tools

Three common uses of measurement are finding linear dimensions, diameters, and angles. Each of these three features can be measured using standard precision devices.

Linear Measurement

The most common linear measurement device is the rule. The most common divisions are sixteenths (1/16 in.) Metric rules are divided in whole millimeters. The part is measured with a rule by aligning one end of the part with the end of the rule or with an inch mark. The linear measurement is taken by reading the rule division at the other end of the part.

Flexible rules are often called tape rules. They are used in woodworking and carpentry applications. There is a hook at one end of the rule that is hooked to the end of the board or structure. The tape is pulled out until it reaches the other end of the board or structure. A measurement is then taken.

Measuring Diameters

A common measurement task involves determining the diameter of round material or parts. Precise diameters can be measured by placing a part between the anvil and the spindle of a micrometer and reading the measurement on the barrel.

Measuring Angles

The angle between two adjacent surfaces is important in many situations. The legs of a desk are generally square (at a 90(angle) with the top. Squares are used to mark angles. The head is placed against one surface of the material. The blade is allowed to rest on an adjacent surface. If the blade touches the surface over its entire length, the part is square (R3, 124-125).

Indirect Reading Measurement Tools

In many modern measuring systems, humans no longer take measurements. Sensors gather the measurement data, which is processed by computers or other automatic devices. The final measurement can be displayed on an output device such as a digital read-out, computer screen, or printout. These new systems include laser measuring devices, optical comparators, and direct reading thermometers.

You may measure length, weight, temperature, or other qualities. However, there must be a reason for doing the measuring. All technological processes produce products or services.

These may be goods, buildings, or communication media.

Measurement is necessary in designing most anything. Its size, shape, or other properties are communicated through measurements. Processing equipment is set up and operated using these design measurements. Materials needed to construct the item are ordered using measurement systems. All personal or industrial production is based on measurement systems.

Measurement can also be used to compare the present condition with a desired condition. The process of setting standards, measuring features, comparing them to standards, and making corrective actions is called quality control. The foundation of a quality control system is measurement and analysis.

Measurement describes distance, mass, time, temperature, number of particles, electrical current, and light intensity. It involves comparing a physical characteristic to an established standard. The common standards are the metric system and the U.S. customary system. These systems allow people to communicate designs, order materials, set up machines, fabricate products, and control quality. (R3)

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1. R1 = Standards for Technological Literacy, page 174

2. R3 = Technology Systems, page 119

3. R3 = Technology Systems, page 121

1. R3 = Technology Systems, page 126

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